The chemical name of brexpiprazole is 7-{4-[4-(1-benzothiophen-4-yl)piperazin-1-yl]butoxy}-1H-quinolin-2-one, and its structural formula is as shown in formula I:

In dopamine D2 receptors, D2 receptor partial agonist can cause functional antagonism to mesolimbic pathway and effectively improve positive symptoms caused by overactive D2 in schizophrenia, while causing functional agonism to mesocortical pathway and improving negative symptoms and cognitive impairment caused by depressed D2 function. Brexpiprazole jointly developed by Lundbeck Pharmaceutical (License) and Otsuka Pharmaceutical (original research) is an experimental serotonin-dopamine activity regulator (SDAM) and it's a medicament for treatment of mental disorders with a novel multi-target mechanism. In addition to the main dopamine D2 receptor partial agonism, brexpiprazole also has D3 receptor partial agonism, 5-HT1A partial receptor partial agonism and 5-HT2A receptor partial antagonism. Therefore, it is a novel medicament with antischizophrenic and antidepressive effect, developed against multiple targets of monoamine neurotransmitter.
In recent years, the polymorphism of drug molecules has attracted more and more attention. The preparation method of dihydrated form of brexpiprazole (the XRPD pattern thereof is shown in FIGS. 3 and 4) and anhydrous form of brexpiprazole (the XRPD pattern thereof is shown in FIG. 5) are reported in the patent applications CN 104254530A and WO 2013/162046. Amorphous brexpiprazole (the XRPD pattern thereof is shown in FIG. 6) and preparation method thereof are reported in CN 201510180947.